I like slightly heavier shafts as well, but like most I find messing around to get things right gets tedious. The thing is, you can do a lot of deciding, you can be the 'decider', I am always struck how nice net length wood shafts fly out of longbows. I use to think that anytime I would put a blunt on an arrow that had been broken at the tip, this is what happens when I shoot at a turkey and hit a tree, that the arrow would fly crazy stiff, but they fly perfect. Go figure. Last season I used some 27" bop 45-50 wapiti cedars for my 53 pound at 26 Morningstar with 145 Grizzly heads, I made some with matching field points. They came in at 454 to 459 grains. I though that my S curve was a little long, so I shortened them to 26.5", perfect. I had one that I broke a target point by hitting an old point in my target and ended up with a net length 145 blunt, which to my surprise flew perfect. That deer I shot did not know that I was under 10 grains per pound. No matter how much calculating you do you will still not know if the same set will fly out of both bows. It would not surprise me at all if you find that the Vixen shoots every bit as hard as the Wesley. I was a bit surprised to find that my Morningstar shoots the same arrow as my 53 pound 62" Robertson and shoots it nearly as fast, average difference 4 fps.